Showing papers on "Clothing insulation published in 2019"

A field investigation on the wintry thermal comfort and clothing adjustment of residents in traditional Nepalese houses

Abstract: Nepal is a landlocked country with geographic variations that have led its people to develop a variety of distinctive cultures. Part of these cultures is reflected in the way that people create a suitable indoor thermal environment in residential buildings, depending on the outdoor climatic conditions . Temperature preferences may vary depending on the local climate characteristics. The aim of this study was to investigate the clothing adaptation of Nepalese residents in traditional houses during the winter. The indoor thermal conditions were examined during a winter in three regions of Nepal with different climates, including cold, temperate and sub-tropical climatic regions. A set of thermal measurements and thermal comfort survey was conducted in traditional houses of selected villages in Mustang, Kavrepalanchok, and Sarlahi districts during the winter of 2016. As part of the survey, 275 votes were collected, while the indoor and outdoor thermal conditions were being recorded in 108 houses. The mean indoor globe temperature was 12.2 °C in the cold region, which was 4.7 °C and 10.0 °C lower than that in the temperate and sub-tropical regions, respectively. The estimated mean comfort globe temperature was 13.8 °C in the cold region, which was 4.1 °C and 9.3 °C lower than that in the temperate and sub-tropical regions, respectively. The difference in the regional comfort temperature is quite large, and this is considered mainly due to differences in the adaptive behavior and particularly the clothing adaptation of the residents in these distinct climatic regions. The mean preferred temperature in the cold region was 14.7 °C, which is slightly higher than its mean comfort temperature. The mean clothing insulation was 1.63 clo in the cold region, and 1.32 clo and 1.15 clo in the temperate and sub-tropical regions, respectively. The choice of clothing and its insulation properties during the winter were mainly based on the condition of the building, indoor and outdoor climatic conditions.

The potential of a modified physiologically equivalent temperature (mPET) based on local thermal comfort perception in hot and humid regions

Abstract: Physiologically equivalent temperature (PET) is a thermal index that is widely used in the field of human biometeorology and urban bioclimate. However, it has several limitations, including its poor ability to predict thermo-physiological parameters and its weak response to both clothing insulation and humid conditions. A modified PET (mPET) was therefore developed to address these shortcomings. To determine whether the application of mPET in hot-humid regions is more appropriate than the PET, an analysis of a thermal comfort survey database, containing 2071 questionnaires collected from participants in hot-humid Taiwan, was conducted. The results indicate that the thermal comfort range is similar (26–30 °C) when the mPET and PET are applied as thermal indices to the database. The sensitivity test for vapor pressure and clothing insulation also show that the mPET responds well to the behavior and perceptions of local people in a subtropical climate.

Investigations on the Winter Thermal Environment of Bedrooms in Zhongxiang: A Case Study in Rural Areas in Hot Summer and Cold Winter Region of China

Abstract: In this paper, onsite measurements and a subjective questionnaire were conducted to study the thermal environment and heating condition of bedrooms during the winter in rural areas in China’s hot summer and cold winter (HSCW) region. Indoor and outdoor thermal environmental parameters were measured to evaluate the thermal conditions of bedrooms. Thermal sensation/tendency/acceptance, heating, and health condition were investigated to complete the analysis of attitudes of local residents on the thermal environment of bedrooms, heating and health issues, as well as the analysis of buildings. The observed results demonstrate that occupants in this region have a strong tolerance to low-temperature environments with the 80% acceptable lower temperature of 4.7 °C and a neutral temperature of 10.7 °C, with an average clothing insulation over 2.2 clo. Oversized volume and acreage of buildings and windows induce a lower temperature in the bedroom. Infants have a significant effect on heating requirements, including heating duration and temperature setpoint. Local residents are highly concerned about the costs, safety, and health related to heating and thermal environments. All evidence obtained through this investigation shows that it is beneficial to formulate regulations for the shape, envelope, and centralized heating policy for rural residential buildings in the HSCW region.

Development of a Data-Driven Predictive Model of Clothing Thermal Insulation Estimation by Using Advanced Computational Approaches

Abstract: Clothing condition was selected as a key human-subject-relevant parameter which is dynamically changed depending on the user’s preferences and also on climate conditions. While the environmental components are relatively easier to measure using sensor devices, clothing value (clo) is almost impossible to visually estimate because it varies across building occupants even though they share constant thermal conditions in the same room. Therefore, in this study we developed a data-driven model to estimate the clothing insulation value as a function of skin and clothing surface temperatures. We adopted a series of environmental chamber tests with 20 participants. A portion of the collected data was used as a training dataset to establish a data-driven model based on the use of advanced computational algorithms. To consider a practical application, in this study we minimized the number of sensing points for data collection while adopting a wearable device for the user’s convenience. The study results revealed that the developed predictive model generated an accuracy of 88.04%, and the accuracy became higher in the prediction of a high clo value than in that of a low value. In addition, the accuracy was affected by the user’s body mass index. Therefore, this research confirms that it is possible to develop a data-driven predictive model of a user’s clo value based on the use of his/her physiological and ambient environmental information, and an additional study with a larger dataset via using chamber experiments with additional test participants is required for better performance in terms of prediction accuracy.

Simulation of PMV and PPD Thermal Comfort Using EnergyPlus

Abstract: This work aims to simulate the thermal comfort for the user of a movie theater in the dimension related to considering the thermal environment parameters by the using EnergyPlus software. The results from simulation are then compared with the experimental ones. In order to calculate and model the thermal comfort, it was necessary a proper characterization of the space that included the measured occupancy, thermal environment variables, distinct electric equipment and lights. To compute the Predicted Mean Vote (PMV) and the Predictable Percentage of Dissatisfied (PPD) in EnergyPlus, the metabolic rate, air velocity and clothing insulation were defined according to the cinema specifications.

Analysis of the effect of using external venetian blinds on the thermal comfort of users of highly glazed office rooms in a transition season of temperate climate – case study

Abstract: Improving the energy efficiency of buildings is among the most urgent social development tasks due to the scale of energy consumption in this industry. At the same time, it is essential to meet high requirements for indoor environmental quality and thermal comfort. The issue of overheating is most often analysed in summer but it also occurs in transition seasons, when the cooling systems do not operate. The paper attempts to evaluate the effectiveness of external mobile shading elements on the microclimate of rooms with large glazed areas in the transition season. Passive solutions, such as shading elements, which limit the increase of indoor temperature, do not always allow the acquisition and maintenance of comfortable solutions for the duration of the season, as demonstrated by the authors. Temporary cooling of the rooms may be necessary to maintain comfortable conditions for the users, or other solutions should be devised to improve comfort (e.g., reduction of clothing insulation characteristics). The novelty of the study consists in the analysis of comfort in a “nearly zero energy consumption” building (NZEB) during a period not analyzed by other scientists. This is a transition period during which heating/cooling systems do not operate. The research task set by the authors involved the assessment of the possibility to reduce office space overheating in the transition season (spring) by using external shading equipment in rooms with large glazed areas. An additional research task aimed at checking the extent to which user behaviour, such as reduction in clothing insulation characteristics, can improve comfort in overheated rooms. The results of the tests reveal that the difference in the ambient air temperature between a room with external venetian blinds and an identical room with no venetian blinds in the transition season, i.e., from 27 March to 6 April 2017, ranged from 12.3 to 2.1 °C. The use of a shading system (external venetian blinds positioned at an angle of 45°) reduced the number of discomfort hours by 92% (during working hours) compared to the room without external venetian blinds. A reduction in the thermal insulation of the clothes worn by people working in the room with no venetian blinds helped to reduce the number of discomfort hours by 31%.

Validation of the Predicted Heat Strain Model in Hot Underground Mines

Abstract: Heat-related illnesses (HRI) are relatively common in both hot surface and underground mining operations. When workers are exposed to extreme heat or strenuous work in a hot environment, they become prone to heat stress. Heat strain is the result of the body’s response to external and internal heat stress. It is therefore vital for the conditions leading to heat strain be detected and treated in a timely manner. Heat-related illnesses are manifested by exhaustion and heat stroke. The predicted heat strain (PHS) [ISO 7933 (2004)] model has been developed to predict the health condition of the worker in terms of core body temperature and water loss. The PHS model tested in this study is based on eight physical parameters that are measured at different intervals during a work shift. They include air temperature, humidity, radiation, air velocity, metabolic rate, clothing insulation, posture, and acclimatization. The model predictions are then compared with a direct physiological measurement, such as core body temperature. We present the results of an extensive study that monitored and predicted body’s response to heat stress under different environmental and working conditions. The PHS model provided reliable results in most instances in comparison with other prediction methods currently in use in the field.

Thermal Comfort Metabolic Rate and Clothing Inference

Abstract: This paper examines the implementation of an algorithm for the prediction of metabolic rate (M) and clothing insulation (\(I_{cl}\)) values in indoor spaces. Thermal comfort is calculated according to Fanger’s steady state model. In Fanger’s approach, M and \(I_{cl}\) are two parameters that have a strong impact on the calculation of thermal comfort. The estimation of those parameters is usually done, utilizing tables that match certain activities with metabolic rate values and garments with insulation values that aggregate to a person’s total clothing. In this work, M and \(I_{cl}\) are predicted utilizing indoor temperature (T), indoor humidity (H) and thermal comfort feedback provided by the building occupants. The training of the predictive model, required generating a set of training data using values in pre-defined boundaries for each variable. The accuracy of the algorithm is showcased by experimental results. The promising capabilities that derive from the successful implementation of the proposed method are discussed in the conclusions.

The relationship between thermal environments and clothing insulation for rural low-income residents in China in winter

Abstract: China is developing rapidly, but there is an obvious imbalance in the development level between urban and rural areas. Differences in economics, living conditions and life style contribute to differences in indoor thermal environments, and may result in differences in the perceptions of thermal comfort between urban and rural areas. Clothing insulation as one of the most important parameters that affect thermal comfort is studied in this research. A field study is conducted in the rural areas of Lankao, China. A total of 384 valid samples were acquired. 54.97% researched houses suffered extreme cold indoor temperatures between 2°C and 6°C. Clothing insulation value of researched population is significantly larger than in other research. Clothing insulation value of female is significantly larger than that of male. It was also found that clothing insulation value correlates positively with age, that clo grow with the increase of age significantly. 7-days running mean outdoor temperature was selected from four temperature indices to predict clothing insulation value. Clo value is negatively correlated with 7-days RM outdoor temperature. But, the slope is quite small in such an extreme cold condition. A case study was conducted to estimate influence of adaptive clothing insulation on heating energy consumption (from Nov. to Mar.). Results show that 863 heating hours are reduced by using adaptive clothing insulation model. The total Heating Degree Hours (HDH) is reduced from 6445 to 1367 by 78.8% which means the same percentage of heating energy conservation. Besides, this case study also concluded that “adaptive clothing insulation model” has higher influence on heating energy consumption in transition season.

Thermal Comfort Study in Naturally Ventilated School Classroom in Parit Raja, Batu Pahat

Abstract: Thermal acceptability among students in classroom is vital for the students’ performance and well-being. The purpose of this study is to assess thermal comfort among school students based on ASHRAE Standard 55-2017. The study of thermal comfort was conducted at Sekolah Kebangsaan Jelutong, Parit Raja involving 56 primary students aged 10 years old in upper-level and ground-level classrooms. Subjective and physical measurement were conducted on both classes. Air velocity, relative humidity, air temperature, mean radiant temperature, and prevailing mean outdoor temperature were measured during physical measurement. Metabolic rate and clothing insulation value were estimated from observation done. Students were given a questionnaire to fill in for identifying their thermal sensation and thermal acceptability during subjective measurement. The physical measurement for upper-level classroom showed less than 80% of acceptability whereas from subjective measurement, the result shows 87% of acceptability. For ground-level classroom, the physical measurement showed 80% of acceptability of thermally condition in the classroom. However, from the subjective measurement, the results show slightly higher of thermally acceptability at 84%. Female students have higher thermal sensation vote’s value because of their clothing insulation value is higher than male students. In conclusion, by comparing both of the classroom, upper-level classroom have higher thermal acceptability than ground-level classroom with the difference of 3% in value.

Evaluating the effect of water-repellent finishing on thermal insulation properties of rowing shirts using a thermal manikin

Abstract: The activity of rowing is majorly performed outside, namely on rivers or lakes, and the probability of getting the t-shirt wet due to splash or rain is high. Since nowadays, one of the problems of rivers and lakes is contaminated water, protecting the rower from that contaminated water in order to prevent skin problems is one of the goals of manufacturers. Thus, the necessity of using a water repellent finishing (WRF) treatment on the rowing clothing may be of importance if health is an issue, although it can also change comfort parameters such as thermal behaviour. In order to evaluate the impact of water repellent finishing on the thermal insulation, several rowing shirts made with different structures and raw material were tested and compared by means of a thermal manikin, before and after finishing. The shirts were treated with a 5% of a fluorocarbon-based product water repellent finishing. The heat loss values of rowing shirts were measured by using a thermal manikin and the effective clothing insulation values were calculated. Moreover, the effect of garment design on thermal insulation was investigated by comparing shirts with more than one knitted structure with single knitting structures shirts. Considering the results for the heat loss values, after WRF, the heat flux of rowing shirts was lower. Shirt B and shirt B-1 had higher effective thermal insulation value after WRF, where the other shirts had lower thermal insulation values. Moreover, not only the water repellent finishing, but also the structure of garment is also important in terms of heat loss and thermal insulation.

Avaliação da eficácia dos equipamentos de proteção individual para a exposição ocupacional ao frio

Abstract: Background The temperature of climate controlled areas in the food industry varies from -35°C to 12°C to ensure the quality of food. However, this temperature range might be harmful to the health of workers. Objective To analyze parameters related to occupational exposure to cold risks to calculate clothing insulation indices and establish the efficacy of personal protective equipment (PPE). Methods In stage 1 we analyzed environmental variables (air temperature and velocity and relative humidity) and the metabolic rate; in stage 2 we calculated the resultant clothing insulation index; in stage 3 we calculated the basic clothing insulation required to maintain the thermal balance and investigated the efficacy of PPE. Results While the air temperature was lower for activities developed in the freezing tunnel (secondary packaging department), required basic clothing insulation was higher for activities involving operating forklifts. Conclusion Protection was efficacious for 83.3% of the analyzed activities, however, occurrence of thermal discomfort cannot be ruled out as a function of excessive clothing. Although protection was insufficient for 16.7% of the analyzed activities, breaks for thermal recovery neutralized the risk of hypothermia.

Practical Estimation Method of Thermal Sensation Using an Infrared Array Sensor

Abstract: In heating, ventilation, and air conditioning control, it is crucial to maintain the comfort of residents. Thermal comfort is typically assessed using the predicted mean vote (PMV) index. PMV depends on six factors: air temperature, mean radiant temperature, air velocity, air humidity, metabolic rate, and clothing insulation. Although PMV can be estimated by measuring these factors directly, this process is costly because multiple sensors are required. Furthermore, measuring metabolic rate and clothing insulation is especially costly because expensive and complex sensors are required. To solve these problems, this paper proposes a practical method for estimating PMV by estimating metabolic rate and clothing insulation using a low-cost infrared array (IrA) sensor. In this study, an IrA sensor called “Grid-EYE” is adopted. PMV parameters other than air velocity and humidity can be measured when the proposed method and an IrA sensor are implemented in an air conditioner. Human detection is done using the temperature map captured by the sensor and their PMV values are estimated individually. Heat sources around people are also detected and their influence on PMV estimation is evaluated. Practical experiments demonstrate the validity of the proposed method by providing estimated PMV values close to theoretical values and real sensations. Therefore, the proposed method can contribute to providing comfortable living spaces and improving energy consumption and amenities efficiently.

Genetic Algorithm Applied to Multi-Criteria Selection of Thermal Insulation on Industrial Shed Roof

Abstract: The rational use of energy has motivated research on improving the energy efficiency of buildings, which are responsible for a large share of world consumption. A strategy to achieve this goal is the application of optimized thermal insulation on a building envelope to avoid thermal exchanges with the external environment, reducing the use of heating, ventilation and air-conditioning (HVAC) systems. In order to contribute to the best choice of insulation applied to an industrial shed roof, this study aims to provide an optimization tool to assist this process. Beyond the thermal comfort and cost of the insulation, some hygrothermic properties also have been analysed to obtain the best insulation option. To implement this optimization technique, several thermo-energetic simulations of an industrial shed were performed using the Domus software, applying 4 types of insulation material (polyurethane, expanded polystyrene, rockwool and glass wool) on the roof. Ten thicknesses ranging from 0.5 cm to 5 cm were considered, with the purpose of obtaining different thermal comfort indexes (PPD, predicted percentage dissatisfied). Posteriorly, the best insulation ranking has been obtained from the weights assigned to the parameters in the objective function, using the technique of the genetic algorithm (GA) applied to multi-criteria selection. The optimization results showed that polyurethane (PU) insulation, applied with a thickness of 1 cm was the best option for the roof, considering the building functional parameters, occupant metabolic activity, clothing insulation and climate conditions. On the other hand, when the Brazilian standard was utilized, rock wool (2 cm) was considered the best choice.

Local thermal discomfort in low temperature environments

Abstract: Human local parts have different thermal responses to low temperature environment. The objective of this paper is to find out the most sensitive parts which are extremely discomforting in low temperature environments. Based on previous experimental data, the relationship among skin temperature, air temperature, and clothing insulation was fitted, and the neutral skin temperatures were obtained. The local skin temperatures at different parts of the human body were compared with neutral skin temperatures in different air temperatures and clothes. The results showed that the local parts of foot, hand, upper arm, and calf deviated far from the neutral condition and were selected as the principal parts to be warmed. The findings are significant to improve human local thermal discomfort.

A Dynamic Convergence Algorithm for Thermal Comfort Modelling.

Abstract: This paper attempts to utilize experimental results in order to correlate clothing insulation and metabolic rate with indoor temperature. Inferring clothing insulation and metabolic rate values from ASHRAE standards is an alternative that totally ignores environmental conditions that actually affect human clothing and activity. In this work, comfort feedback regarding occupants’ thermal sensation is utilized by an algorithm that predicts clothing insulation and metabolic rate values. The analysis of those values reveals certain patterns that lead to the formulation of two non-linear equations between clothing – indoor temperature and metabolic rate – indoor temperature. The formulation of the equations is based on the experimental results derived from the thermal comfort feedback provided by actual building occupants. On trial tests are presented and conclusions regarding the method’s effectiveness and limitations are drawn.

Thermal Environment in Kitchen

Abstract: This chapter provides an introduction to kitchen thermal environment and how it can be measured and evaluated. Thermal comfort is influenced by personal factors (activity and clothing insulation) and environmental factors (air temperature, mean radiant temperature, relative humidity, and air velocity). Additionally, kitchen thermal environment is influenced by many factors that include the heat load of all kinds of cooking appliances, human body, lighting, and the envelope.